Generally yes, verbs ended by -ся (reflexive)are normally equivalent of English passive voice. But in fact sometimes there are additional meanings or nuances.

For example "интересоваться кем-то" most probably means either "to ask around about someone" or "to show the interest". In perfective (поинтересоваться) it means just "to ask". "Интересоваться чем-то" sometimes means "something is my hobby".